Control station, mobile station, mobile communication system and mobile communication method

ABSTRACT

A mobile station that establishes a first transfer path by way of a first access network between the mobile station and a control station. The mobile station establishes a default EPS (Evolved Packet System) bearer by way of a second access network between the mobile station and the control station by transmitting an attach request for requesting a handover of a partial flow among the plurality of flows when performing transmission/reception of a plurality of flows with the control station by using the first transfer path.

This application is a Continuation of co-pending application Ser. No.13/127,727 filed on May 5, 2011, and for which priority is claimed under35 U.S.C. §120, application Ser. No. 13/127, 727 is the national phaseof PCT International Application No. PCT/JP2009/068750 filed on Nov. 2,2009 under 35 U.S.C. §371, which claims the benefit of priority ofJP2008-285689 filed Nov. 6, 2008. The entire contents of each of theabove-identified applications are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a control station or the like which isset with a mobile station connectable to a first access network capableof establishing a bearer transfer path that guarantees a predeterminedQoS and a second access network different from the first access network;and a path for performing communication of a plurality of flows by wayof the second access network. The control station includes: an attachrequest receiving means that receives an attach request in order for themobile station to perform a handover from the second access network tothe first access network; and a bearer establishing means thatestablishes a bearer on the first access network when receiving theattach request.

BACKGROUND ART

Conventionally, in mobile communication systems, there have been variousknown techniques to control the handoverof a mobile station betweendifferent networks (e.g., between a 3GPP standard network and a WLAN, orthe like).

Mobile control (handover) in the conventional mobile communicationnetworks is defined in non-patent document 1 and non-patent document 2,for example. Now, a conventional mobile communication system will bedescribed with reference to FIG. 13. A mobile communication system 9 inFIG. 13 is an embodiment of a mobile communication system described innon-patent document 1.

In mobile communication system 9 in FIG. 13, a plurality of accessnetworks (access network A, access network B) are connected to a corenetwork. A UE (User Equipment; mobile station) 910 is also connected tothe core network via an access network. UE 910 is connectable to thecore network by way of either access network A or access network B.

Here, access network A is a communication path for which QoS can be set,for example a network defined by the 3GPP standard. Provided for accessnetwork A is an eNB (base station) 950 to which UE 910 is connected. UE910 is connected to the core network via eNB 950 and a gateway SGW(Serving GW) 940.

Further, a PGW (Packet Data Gateway: control station) 920 forwardingcommunication data to UE 910 is installed in the core network. PGW 920is connected to access network A via SGW 940.

Further, provided for the core network is a MME (Mobility ManagementEntity: management station) 930 which receives a request for transferpath establishment from UE 910 and takes control of the procedure ofestablishing an EPS bearer as a transfer path between UE 910 and PGW 920via eNB 950 and SGW 940. The EPS bearer is a transfer path between UE910 and PGW 920 by way of access network A.

On the other hand, access network B is provided with an AR (AccessRouter) 960 to which UE 910 connects, so that UE 910 is connected withPGW 920 in the core network via AR 960 by establishing a transfer pathbased on DSMIPv6 (Dual-Stack MIPv6) (e.g., see non patent document 3).

UE 910 is connected to PGW 920 by a transfer path, either the DSMIPv6transfer path or the EPS bearer. A similar transfer path is establishedat a UE at the other communication end, so that communication betweenUEs are performed using respective communication paths via PGW 920.

Further, there is a defined handover procedure relating to a case wherecommunication that UE 910 is transmitting/receiving by way of theDSMIPv6 transfer path via access network B is changed over to the bearertransfer path via access network A to continue communication.

PRIOR ART DOCUMENTS Non-Patent Document

-   Non-Patent Document 1: TS23.402 Architecture enhancements for    non-3GPP accesses-   Non-Patent Document 2: TS23.401 General Packet Radio Service (GPRS)    enhancements for Evolved Universal Terrestrial Radio Access Network    (E-UT RAN) access-   Non-Patent Document 3: Mobile IPv6 Support for Dual Stack Hosts and    Routers, draft-ietf-next-memo-v4traversal-05.txt

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The transmission capacity of the communication path in the conventionalmobile communication system (packet communication system) was low inspeed while there were no applications that essentially need broadbandcommunication. Therefore, it was not necessary to perform complicatedcontrol such as to providing for each application an individualcommunication path allotted with a bandwidth required for thatapplication.

However, in recent years, applications have become diversified with theexplosive spread of the internet. Various types have become general,such as WEB access, FTP and the like that do not need to securebandwidth which is equal or greater than a predetermined value, voicecommunication and the like that do not need a large bandwidth but needto have the least minimum bandwidth, and those, such as videodistribution and others, that have difficulty in operation if a largebandwidth is not assured.

If a transfer path can be secured for an application in conformity withthe characteristic of that application, it is possible to prevent atransfer path having a too large bandwidth from being allotted to anapplication that does not need to have that large bandwidth, and it isalso possible to allot a large enough bandwidth to an application thatdoes need to have a large bandwidth, thus making it possible to makeefficient use of the band.

Also in the above-described conventional technology, schemes ofperforming communication by establishing a bearer as a communicationpath that satisfies the QoS levels needed by applications, have becomeoffered, so that technologies that satisfy both the efficient band usageand maintenance of communication quality have come to be established.

However, there still exists an insufficient part in performing ahandover function while keeping quality, in the network in which a UEconnects to a core network via an access network having a QoS guaranteefunction and a plurality of access networks having a QoS guaranteefunction.

In the above-described conventional technology, when UE 910 that isperforming communication by way of DSMIPv 6 transfer path via accessnetwork B performs a handover to access network A, it was necessary toestablish a bearer as a communication path via access network A firstand change all of communications that UE 910 is making, from the DSMIPv6communication path to the bearer communication path at a time.

Here, it is possible to presume a situation in which UE 910 isperforming a plurality of flows of communication through the DSMIPv6communication path. A flow is a communication classification that can beidentified based on the application or the party at the other end. Forexample, an application such as a voice communication or WEB access canbe identified as a different flow.

In conventional handovers, the communication paths of UE 910 and PGW 920were not controlled as to flows, and it was necessary to hand over allthe flows of a UE by changing the communication paths all at once at thetime of a handover. Specifically, when a handover is performed from astate in which a voice communication flow ‘a’ and a WEB access flow ‘b’are being practiced through the DSMIPv6 transfer path, a bearer as acommunication path via access network A is established first, then thecommunication paths for flow ‘a’ and flow ‘b’ are changed over in UE 910and PGW 920 from the DSMIPv6 transfer path to the bearer transfer pathto achieve a handover. That is, the bearer communication path and theDSMIPv6 transfer path could not be held simultaneously.

Access network A and access network B can be constructed of differentaccess networks, such as LTE (Long Term Evolution), radio LAN and thelike, and these networks are different in transmission rate, presence orabsence of QoS and other performance. On the other hand, applicationsare different in demanded transmission rate, necessity of QoS and othercharacteristics, depending on the property of each application.Accordingly, the suited access network is different depending on theflow, but in the prior art, there was no means that controls thetransfer paths for flows, so that it was impossible to hand over aspecific flow alone.

Further, in the prior art, defined as the bearers of the transmissionpaths to be established via access network A are a default bearer (EPSbearer 1) that does not guarantee QoS and is not for a specific flow,and a specific EPS bearer (EPS bearer 2) that guarantees QoS forspecific flows.

However, since, in the prior art, it is impossible to perform a handoverby a unit of flow, no consideration as to QoS is given. When a handoverfrom the DSMIPv6 transfer path is performed, it is necessary toestablish the default bearer and then perform a handover to the defaultbearer. It is possible to establish a specific EPS bearer aftercontinuation of communication through the default bearer so as to enablecommunication through the specific EPS bearer that satisfies thenecessary QoS for the flow. However, since it is necessary totemporarily perform communication using the default bearer that does notsatisfy the QoS level, there occurs the problem that the quality of theflow is markedly degraded at that time.

In the above way, in the prior art, it was impossible to perform ahandover by a unit of flow to an access network capable of performingbearer communication, hence there has been the problem that it isimpossible to implement a handover of a flow to the bearer with its QoSmaintained even though a bearer that supports the QoS can beestablished.

In view of the above-described problem, it is therefore an object of thepresent invention to provide a mobile communication system or the likein which when a mobile station performs a handover, a specific flowamong a plurality of flows is selected and directly handed over to abearer communication path so as to be able to achieve a handover whilekeeping communication quality.

Means for Solving the Problems

In view of the above problems, a control station of the presentinvention is a control station which is set with: a mobile stationconnectable to a first access network capable of establishing a bearertransfer path that guarantees a predetermined QoS and a second accessnetwork different from the first access network; and a path forperforming communication of a plurality of flows by way of the secondaccess network, the control station comprising: a bearer establishmentmeans for establishing a bearer on the first access network when thecontrol station receives a handover request for a handover from thesecond access network to the first access network, from the mobilestation; a specific bearer establishment means that receives a specificbearer establishment request including information on a flow for which aQoS is guaranteed, from the mobile station, and establishes a specificbearer that guarantees the QoS of the flow, based on the specific bearerestablishment request; and a path setting means that sets up a path forperforming communication of the flow between the mobile station and thecontrol station, on the specific bearer.

The control station of the present invention is characterized in thatfor other than the flow included in the specific bearer establishmentrequest, communication is continued through the path set on the secondaccess network.

The control station of the present invention is characterized in thatthe specific bearer establishment means establishes the specific bearerwhen a position register request that the mobile station transmits aftera handover includes information on a flow for which QoS is guaranteed.

The control station of the present invention is characterized in that amanagement station that receives an attach request as a handover requestfrom the mobile station and transmits a bearer establishment request tothe control station in accordance with the attach request, is connectedto the first network, and, the bearer establishment means, whenreceiving the bearer establishment request from the management station,establishes a bearer on the first access network.

The control station of the present invention is characterized in that amanagement station that receives the specific bearer establishmentrequest from the mobile station and transmits the specific bearerestablishment request to the control station, is connected to the firstnetwork, and, the specific bearer establishment means, when receivingthe specific bearer establishment request from the management station,establishes the specific bearer that guarantees the QoS of the flow.

A control station of the present invention is a control station which isset with a mobile station connectable to a first access network capableof establishing a bearer transfer path that guarantees a predeterminedQoS and a second access network different from the first access network,and a path for performing communication of a plurality of flows by wayof the second access network, the control station comprising: a handoverrequest receiving means that receives a handover request for the mobilestation to perform a handover from the second access network to thefirst access network, the handover request including information on aflow for which QoS is guaranteed; a specific bearer establishment meansthat establishes a specific bearer that guarantees the QoS of the flow,based on the handover request; and, a path setting means that sets up apath for performing communication of the flow between the mobile stationand the control station, on the specific bearer.

Further, a mobile station of the present invention is a mobile stationwhich is connectable to a first access network capable of establishing abearer transfer path that guarantees a predetermined QoS and a secondaccess network different from the first access network, and is set witha path for performing communication of a plurality of flows by way ofthe second access network and a control station, the mobile stationcomprising: a handover request transmitting means that transmits ahandover request to the control station when the mobile station ishanded over from the second access network to the first access network;and, a specific bearer request means for requesting the control stationto establish a specific bearer that guarantees the necessary QoS for aflow.

The mobile station of the present invention is characterized in that anattach request transmitted by the handover request transmitting means istransmitted including information on a flow for which QoS is guaranteed.

A mobile communication system of the present invention is a mobilecommunication system comprising: a mobile station connectable to a firstaccess network capable of establishing a bearer transfer path thatguarantees a predetermined QoS and a second access network differentfrom the first access network; and a control station set with a path forperforming communication of a plurality of flows by way of the secondaccess network, the control station comprising: a bearer establishmentmeans for establishing a bearer on the first access network when thecontrol station receives a handover request for performing a handoverfrom the second access network to the first access network, from themobile station, the mobile station comprising: a handover requesttransmitting means that transmits the handover request to the controlstation when the mobile station performs the handover from the secondaccess network to the first access network; and, a specific bearerrequest means for requesting the control station to establish a specificbearer that guarantees the necessary QoS for a flow, the control stationfurther comprising: a specific bearer establishment request receivingmeans for receiving a specific bearer establishment request, includinginformation on a flow for which QoS is guaranteed; a specific bearerestablishment means for establishing a specific bearer that guaranteesthe QoS of the flow, based on the specific bearer establishment request;and a path setup means for setting up a path for performingcommunication of the flow between the mobile station and the controlstation, on the specific bearer.

A mobile communication method of the present invention is a mobilecommunication method including: a mobile station connectable to a firstaccess network capable of establishing a bearer transfer path thatguarantees a predetermined QoS and a second access network differentfrom the first access network; and a control station set up with a pathfor performing communication of a plurality of flows by way of thesecond access network, the method comprising: the step in which themobile station transmits a handover request to the control station whenthe mobile station performs a handover from the second access network tothe first access network; the step in which the control stationestablishes a bearer on the first access network based on the handoverrequest; the step in which the mobile station requests the controlstation to establish a specific bearer that guarantees the necessary QoSfor a flow; the step in which the control station receives the requestfor the specific bearer and establishes the specific bearer thatguarantees the QoS of the flow; and, the step of setting up a path forperforming communication of the flow between the mobile station and thecontrol station, on the specific bearer.

Advantages of the Invention

According to the present invention, the control station is set with amobile station connectable to a first access network capable ofestablishing a bearer transfer path that guarantees a predetermined QoSand a second access network different from the first access network anda path for performing communication of a plurality of flows by way ofthe second access network. The control station establishes a bearer onthe first access network when receiving a handover request for ahandover from the second access network to the f first access network,from the mobile station; and receives a specific bearer establishmentrequest including information on a flow for which a QoS is guaranteed,from the mobile station, establishes a specific bearer that guaranteesthe QoS of the flow, based on the specific bearer establishment request;and sets up a path for performing communication of the flow between themobile station and the control station, on the specific bearer.

Accordingly, at the time of a handover, a flow for which QoS isguaranteed can be put in communication, not through the bearerestablished in the first access network, but through a path that is setup on the specific bearer.

According to the present invention, for other than the flows included inthe specific bearer establishment request, communication can becontinued through the path set on the second access network.Accordingly, it is possible to perform communication by setting paths onboth the first access network and the second access network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for illustrating the overall scheme of a mobilecommunication system in the present embodiment.

FIG. 2 is a diagram for illustrating the configuration of a UE (mobilestation) in the present embodiment.

FIG. 3 is a diagram for illustrating the configuration of a PGW in thepresent embodiment.

FIG. 4 is a diagram for illustrating one data configuration example offlow management tables in the present embodiment.

FIG. 5 is a diagram for illustrating the procedure of communication pathestablishment in the present embodiment.

FIG. 6 is a diagram for illustrating the processing flow in the firstembodiment.

FIG. 7 is a diagram for illustrating one data configuration example offlow management tables in the first embodiment.

FIG. 8 is a diagram for illustrating the processing flow in the firstembodiment.

FIG. 9 is a flow chart for illustrating the operation of a PGW in thefirst embodiment.

FIG. 10 is a diagram for illustrating the processing flow in the secondembodiment.

FIG. 11 is a diagram for illustrating the processing flow in the thirdembodiment.

FIG. 12 is a diagram for illustrating the processing flow in the fourthembodiment.

FIG. 13 is a diagram for illustrating the overall scheme of aconventional mobile communication system.

MODES FOR CARRYING OUT THE INVENTION

Referring next to the drawings, the embodiments of a mobilecommunication system to which the present invention is applied will bedescribed in detail.

[1. Network Configuration]

To begin with, the network configuration in the present embodiments willbe described with reference to FIG. 1. FIG. 1 is a diagram forillustrating the overall scheme of a mobile communication system 1 whenthe present invention is applied. As shown in this figure, in the mobilecommunication system, an access network A and an access network B areconnected to a core network. Here, access network A and access network Bare assumed to be different networks; for example, access network A isassumed to be a 3GPP standardized network while access network B isassumed to be a non-3GPP network (e.g., DSMIPv6) as an example.

First, a UE 10 (mobile station: User Equipment) is connected to the corenetwork via a plurality of radio access networks. Access network Aincludes a base station (eNB 50) to which UE 10 connects and isconnected to the core network via a gateway (SGW 40).

The core network is installed with a GW (PGW 20) that forwards thecommunication data transmitted from other mobile stations to a mobilestation and is connected to SGW 40. Further, the core network isinstalled with a management apparatus (MME 30) that receives a requestfor transfer path establishment from UE 10 and takes control of theprocedure for establishing a bearer (EPS bearer) as a transfer pathbetween UE 10 and PGW 20 via eNB 50 and SGW 40. The EPS bearer is aQoS-supporting transfer path between UE 10 and PGW 20 by way of accessnetwork A.

Access network B is installed with an access router (AR 60) to which UE10 connects, so that UE 10 is connected with PGW 20 in the core networkvia AR 60 by establishing a transfer path based on DSMIPv6.

Access network A is, for example a LTE (Long Term Evolution) as a radioaccess network that is defined by 3GPP as a communicationstandardization organization for mobile phone networks. Access network Bis an access network such as a radio LAN, WiMAX or the like. The corenetwork is based on SAE (System Architecture Evolution) defined by 3GPP.

As above, in the mobile communication system using packet communicationin the present embodiment, UE 10 is connected to the core network by thetransfer path of the bearer that supports QoS via access network A andby the transfer path based on DSMIPv6 via access network B.

[2. Equipment Configurations]

Subsequently, each apparatus configuration will be briefly describedwith reference to the drawings. Here, SGW 40, MME 30, eNB 50 and AR 60have the same configurations as those of the conventional equipment inSAE, so that detailed description is omitted.

[2.1 UE Configuration]

First, the configuration of UE 10 as a mobile station will be describedusing a block diagram in FIG. 2. Here, as a specific example of UE 10, aterminal such as mobile terminal, PDA or the like, which simultaneouslyconnects to the core network via a plurality of access networks, issupposed.

As shown in FIG. 2, UE 10 includes a controller 100, a first transceiver110, a second transceiver 120, a storage 130, a bearer establishmentprocessor 140, a DSMIPv6 processor 150 and a packet transceiver 160.

Controller 100 is a functional unit for controlling UE 10. Controller100 reads out and executes various programs stored in storage 130 torealize processes.

First transceiver 110 and second transceiver 120 are functional unitsfor enabling UE 10 to access each access network. First transceiver 110is the functional unit for connection to access network A and secondtransceiver 120 is the functional unit for connection to access networkB. Connected to first transceiver 110 and second transceiver 120 areexternal antennas, respectively.

Storage 130 is a functional unit for storing programs, data, etc.,necessary for UE 10 to perform various kinds of operations. Storage 130further stores a flow management table 132 for storing flow informationfor identifying applications in association with transfer paths fortransmission. This flow management table 132 is referred to when packettransceiver 160 transmits data so as to select a transfer path for eachflow, whereby the data is transmitted from the transceiver correspondingto the transfer path.

Here, FIG. 4( a) shows one data configuration example of the flowmanagement table. As shown in FIG. 4( a), a flow (e.g., “flow 1 (TFT1,FlowID1)” is stored corresponding to a transfer path (e.g., “DSMIPv6transfer path”).

Bearer establishment processor 140 is a functional unit that executes aprocess for establishing an EPS bearer as a communication path to PGW 20via access network A, by way of SGW 40.

DSMIPv6 processor 150 is a functional unit for establishing a transferpath based on DSMIPv6 to connect to the core network via access networkB. Packet transceiver 160 is a functional unit that transmits andreceives specific data (packets). The unit decomposes the data receivedfrom the upper layer into packets to be transmitted. The unit alsorealizes a function of transferring received packets to the upper layer.

[2.2 PGW Configuration]

Next, the configuration of PGW 20 in the present embodiments will bedescribed based on FIG. 3. PGW 20 includes a controller 200, atransceiver 210, a storage 230, a bearer establishment processor 240, aDSMIPv6 processor 250 and a packet transceiver 260.

Transceiver 210 is a functional unit that is wired to a router or aswitch to transmit and receive packets. For example, this unit performstransmission and reception using Ethernet (registered trademark) that isusually used as a network connecting system, or the like.

Storage 230 is a functional unit for storing programs, data, etc.,necessary for PGW 20 to execute various operations. Storage 230 furtherstores a flow management table 232 for storing flow information foridentifying applications in association with transfer paths fortransmission. Flow management table 232 is referred to when packettransceiver 260 transmits data so as to select a transfer path for eachflow, whereby the data is transmitted from the transceiver correspondingto the transfer path.

Here, FIG. 4( b) shows one data configuration example of the flowmanagement table. As shown in FIG. 4( b), a flow (e.g., “flow 1 (TFT1,FlowID1)” is stored corresponding to a transfer path (e.g., “DSMIPv6transfer path”).

Bearer establishment processor 240 is a functional unit that executes aprocess for establishing an EPS bearer as a communication path to UE 10via access network A, by way of SGW 40.

DSMIPv6 processor 250 is a functional unit for establishing a transferpath based on DSMIPv6 to connect to UE 10 via access network B. Packettransceiver 260 is a functional unit that transmits and receivesspecific data (packets).

[3. Communication Path Establishment Procedure]

Next, in the network shown in FIG. 1, the procedures of UE 10, AR 60 andPGW 20 when UE 10 connects to the core network via access network B toestablish a DSMIPv6 communication path, will be described using asequence diagram in FIG. 5. Here, UE 10 transmits and receives controlinformation by means of second transceiver 120 connected to accessnetwork B to achieve the procedure.

(1) First, UE 10 performs an authentication procedure for acquiring alocal IP address from access network B (S100). The procedure is executedby the combination of the procedure between UE 10 and AR 60 and theprocedure between AR 60 and PGW 20, as the method conventionally donefor DSMIPv6. AR 60 is installed in the coverage area for UE 10, and isthe AR that UE 10 connects. PGW 20 is an entity that is selected basedon the information previously held by UE 10. An authentication andaccess permission processes are performed by PGW 20 or AR 60, using theprofiles such as the identification information of UE 10, the subscriberdata, etc., based on the service policy.

(2) Then, the UE 10 that is authorized and permitted to access isassigned a local IP address by AR 60, as in the conventional method ofDSMIPv6 (S102). The assigned local IP address is an IPv4 or IPv6address, and is used as CoA (Care-of-Address) of DSMIPv6. The method ofassignment is implemented based on DHCP that is widely used in theInternet or a stateless IP address assignment procedure.

(3) A setup process for establishing security association fortransmitting/receiving encrypted DSMIPv6 control messages between UE 10and PGW 20 is implemented (S104). This process is performed based onIKEv2, EAP or the like, following the conventional DSMIPv6 technique.

At this step, PGW 20 gives notice of an IPv6 Address or IPv6 networkprefix to UE 10. UE 10 sets the assigned IPv6 address as HoA (HomeAddress). When a network prefix is assigned, HoA is generated based onthat network prefix. By this procedure, UE 10 becomes able to perform aposition registering process in safety, to PGW 20, using an encryptedcontrol message.

(4) UE 10 transmits a position register request defined in DSMIPv6 toPGW 20 (S106). The message includes the identification information of UE10, HoA of UE 10 and CoA as positional information. UE 10 can also makea request for assignment of HoA in IPv4 address, by this message basedon DSMIPv6.

Here, UE 10 transmits a position register request including flowinformation for which communication is performed using a DSMIPv6transfer path to be generated. The flow information is information thatenables distinction between applications, and the TFT (Traffic FlowTemplate) formed of an IP address, port number and protocol number canbe used.

Further, it is possible to use a flow ID as the flow information whenboth UE 10 and PGW 20 share ‘TFTs’ and ‘flow IDs for identifying TFTs inadvance. Further, the position register request may include a pluralityof flow information.

In the present embodiment, the request is transmitted including flow 1identified by TFT1 and flow 2 identified by TFT2. For example, flow 1may be for an application such as voice communication and flow 2 may befor an application such as WEB access or the like.

(5) PGW 20 establishes a DSMIPv6 transfer path and transmits a positionregister response to UE 10 (S108). The position register responseincludes HoA and CoA. It is also possible to assign HoA in an IPv4address by the request in (4) (the request at S106). Further, the UEhaving received the position register response also completes a transferpath establishment process.

(6) UE 10 and PGW 20 start data transmitting/receiving through theestablished DSMIPv6 transfer path (S110). That is, in DSMIPv6 transferpath, a path is set up between PGW 20 and UE 10.

By the steps as above, the DSMIPv6 transfer path is established betweenUE 10 and PGW 20. In PGW 20, the transfer path for transmitting flows ofUE 10 is controlled by making the flows correspondent to the transferpath established by DSMIPv6, as shown in FIG. 4( b). Specifically, flow1 and flow 2 are controlled so as to be transmitted to UE 10 throughDSMIPv6 transfer path.

Similarly, in UE 10, the transfer path for transmitting flows of UE 10is controlled by making the flows correspondent to the transfer pathestablished by DSMIPv6, as shown in FIG. 4( a). Specifically, flow 1 andflow 2 are controlled so as to be transmitted to UE 10 through DSMIPv6transfer path. In UE 10 and PGW 20, when packets are transmitted,packets are transmitted by referring to the flow management table toselect a transfer path corresponding to the flow of transmission data.The same procedure is implemented at the other end of UE 10, so thatcommunication between mobile stations is enabled by way of PGW 20.

Thereafter, if communication of an additional flow is wanted through theDSMIPv6 transfer path, it is possible to perform registration of theflow by implementing a position registering procedure added with flowinformation.

[4. Handover Procedure]

Next, the procedure when a mobile station is handed over from accessnetwork B to access network A will be described.

4.1 The First Embodiment

To being with, the first embodiment will be described with reference toFIGS. 6 to 9.

[4.1.1 Attachment Type 1 Case]

First, description will be given with reference to FIG. 6. As theinitial state at the time of a handover, UE 10 is performingcommunication of flow 1 and flow 2 through the DSMIPv6 transfer path byway of access network B (S200). At the time of a handover, UE 10 entersthe coverage area of base station (eNB 50) of access network A andperforms a handover procedure for transmitting/receiving the controlmessages by means of first transceiver 110.

(1) Following the conventional method, UE 10 transmits a handoverrequest. Specifically, UE 10 sends an attach request to MME 30 first(S202). The attach request includes identification information on UE 10for authenticating UE 10 and permitting access. This also includes anaccess point name (APN) for identifying the PGW 20 to be connected to.

Here, the difference from the prior art is that UE 10 can give notice ofa new attachment type, by use of an information element of the attachrequest. The new attachment type represents making a request for ahandover of a specific flow that is communicated through another accessnetwork. This indicates a request that PGW 20 will not transmit packetsto UE 10 through the default bearer as the transfer path that isestablished first in the conventional handover procedure.

On the other hand, since the conventional attach request at the time ofa handover does not perform control by a unit of flow, all the flowsthat UE 10 is communicating are handed over. The following descriptionwill be given assuming that attachment type “1” is the new attachmenttype and attachment type “2” is a conventional attach request. That is,

Attachment type 1: an attachment that represents a handover from anotheraccess network and performing a handover of a specific flow

Attachment type 2: an attachment that represents a handover from anotheraccess network and performing a handover of all the flows.

As a specific method of notifying the attachment type, a new flowhandover flag (which will be referred to hereinbelow as “F flag”) isdefined in the attach request such that setting “F flag” “ON” canindicate attachment type “1” and setting “F flag” “OFF” can indicateattachment type “2”. First, FIG. 6 illustrates an example where anattach request in attachment type “1” is made.

(2) MME 30 having received the attach request executes an authenticationand access permission processes by performing a procedure between UE 10and eNB 50, following the conventional method (S204). MME 30 performsauthentication and access permission based on subscriber identificationinformation and the like of UE 10 included in the attachmentinformation.

(3) MME 30 executes an establishment process of the default EPS bearer(EPS bearer 1) for UE 10 that was permitted to connect (S206). Theprocedure is performed following the conventional procedure, bytransmitting/receiving control messages between UE 10, eNB 50, MME 30,SGW 40 and PGW 20.

Specifically, MME 30 having received an attach request, transmits adefault EPS bearer establishment request to PGW 20. PGW 20, as receivingthe default EPS bearer establishment request, executes a process ofestablishing an EPS bearer. Herein, the difference from the prior art isthat the default EPS bearer establishment request includes theattachment type (attachment type “1” in this case) included in theattach request. Here, the default EPS bearer is not a transfer path thatsatisfies the QoS level required by the specific flow but a transferpath for enabling communication between UE 10 and PGW 20.

(4) After establishment of the default EPS bearer, UE 10 transmits aspecific EPS bearer establishment request to MME 30 (S208). The messageherein includes, as the information on a flow to be handed over, flowidentification information and its QoS level. The flow identificationinformation is information that enables identification of theapplication and can use the TFT (Traffic Flow Template) formed of an IPaddress, port number and protocol number. It is also possible to use theflow ID as the flow information when both UE 10 and PGW 20 have sharedflow IDs identifying TFTs in advance. With this, UE 10 gives notice ofthe flow for which a handover is demanded and the QoS levelcorresponding to the flow (the QoS level to be guaranteed for the flow).In the present embodiment, as the TFT included in the flowidentification information, “TFT1” is specified.

(5) MME 30 receives the specific EPS bearer establishment request fromUE 10 and executes an establishment process of a specific EPS bearer(EPS bearer 2) (S210). The procedure for the EPS bearer establishmentprocess is executed following the conventional procedure, bytransmitting a specific EPS bearer establishment request from MME 30 toPGW 20 and then transmitting/receiving control messages between UE 10,eNB 50, MME 30, SGW 40 and PGW 20. The specific EPS bearer is a transferpath that guarantees the QoS level required for the specific flowrequested by UE 10 and a transfer path for enabling communicationbetween UE 10 and PGW 20.

(6) PGW 20 transmits a flow (TFT1) selected by the request of UE 10 fromthe flows of UE 10 having been transmitted through the DSMIPv6 transferpath, by the transfer path of EPS bearer 2, to UE 10. That is, for theselected flow (TFT1) a path is set up in EPS bearer 2 so that datatransmission/reception of TFT1 is started by use of the transfer path ofEPS bearer 2 (S212).

As described above, though in the conventional handover, in performing ahandover it was necessary to perform a handover once to the default EPSbearer that does not satisfies the QoS level, it is possible to performa handover to the specific EPS bearer that guarantees the QoS levelnecessary for the flow, without using the default EPS bearer.Accordingly, it becomes possible to switch the transfer path withoutdegrading communication quality in the application.

Specifically, UE 10 transmits a specific EPS bearer establishmentrequest by specifying flow 1 (TFT1) to establish EPS bearer 2 thatguarantees the QoS level of flow 1. FIG. 7( a) shows a flow managementtable 132 of UE 10 in this case. FIG. 7( b) shows a flow managementtable 132 of PGW 20. In this way, the transfer path of flow 1 is updatedto EPS bearer 2 in UE 10, and the transfer path of flow 1 is updated toEPS bearer 2 in PGW 20.

In transmitting packets, in UE 10 and PGW 20, packets are transmitted byidentifying the flow based on the transmission data with reference tothe flow management table so as to select the transfer pathcorresponding to the flow. On the other hand, flow 2 that is notincluded in the specific EPS bearer establishment request is keptcommunicating through the DSMIPv6 transfer path.

(7) After establishment of the specific EPS bearer UE 10 transmits aposition register request to PGW 20, based on DSMIPv6 (S214). Themessage includes the identification information of UE 10, HoA of UE 10and CoA as positional information. Further, UE 10 transmits the flowinformation for performing communication using the established DSMIPv6transfer path, with the position register request.

(8) PGW 20 transmits a position register response to UE 10 to completethe position registering process of DSMIPv6 (S216).

As a result of the above procedure, it becomes possible to perform ahandover of a unit of flow from access network B to access networkAwhile keeping the QoS. In the prior art, when a plurality of flowsproceed in communication, all the flows have to be handed over at once.Hence it was impossible to select an access network (transfer path)suited to each of the flows.

Accordingly, as a result of the present embodiment, for example anaccess network having a large enough bandwidth is selected for a flowthat needs a greater bandwidth while other access networks are allottedto other flows, whereby it is possible to make use of transmission pathmore suited to flow, and hence use resources efficiently.

Here, though it was assumed that switching of transfer paths at PGW 20is implemented immediately after establishment of the specific EPSbearer at S210, the switching may also be triggered by the positionregistering procedure of DSMIPv6 shown at S214 and S216.

Further, though description was made that the position registerrequest/response are given after establishment of the specific EPSbearer (EPS bearer 2), position register complete notice/response fromPGW 20 to UE 10 may also be given. That is, PGW 20 transmits a positionregister complete notice that indicates that position registration of UE10 after a handover is completed, to UE 10. UE 10 transmits a responsesignal that acknowledges the reception of the position register completenotice, to PGW 20. Further, switching of transfer paths at PGW 20 may betriggered by the position register complete notice/response procedurefrom PGW 20 to UE 10.

[4.1.2 Attachment Type 2 Case]

Subsequently, a case when the attachment type is “2” will be describedwith reference to FIG. 8.

As the initial state at the time of a handover, UE 10 is performingcommunication of flow 1 (TFT1) and flow 2 (TFT2) through the DSMIPv6transfer path by way of access network B (S300) as a result of thecommunication path establishment procedure described heretofore. At thetime of a handover, UE 10 enters the coverage area of base station (eNB50) of access network A and transmits a handover request by a controlmessage using first transceiver 110 to execute a handover procedure.

(1) UE 10 transmits an attach request as a handover request to MME 30,following the conventional method (S302). The attach request includesidentification information on UE 10 for authenticating UE 10 andpermitting access. This also includes an access point name (APN) foridentifying the PGW 20 to be connected to. Here, UE 10 makes an attachrequest as attachment type “2” by non-inclusion of F-flag.

(2) Similarly to (2) for attachment type “1”, an authentication andaccess permission processes are executed (S304).

(3) Similarly to (3) for attachment type “1”, MME 30 executes anestablishment process of the default EPS bearer (EPS bearer 1) for UE 10that was permitted to connect (S306). Thereby, the default EPS bearer(EPS bearer 1) is establishment between UE 10 and PGW 20. That is, MME30 having received the attach request, transmits a default EPS bearerestablishment request to PGW 20. The default EPS bearer establishmentrequest includes the attachment type (attachment type “2” in this case)included in the attach request.

(4) Since the attach type is “2”, the paths for flow 1 and flow 2 areset up for PGW 20 by way of EPS bearer 1. That is, datatransmission/reception of flow 1 and flow 2 (TFT1 and TFT2) is startedin EPS bearer 1 (S308).

(5) UE 10 transmits a position register request to PGW 20 afterestablishment of the specific EPS bearer (S310).

(6) PGW 20 transmits a position register response to UE 10 to completethe position registering process (S312).

(7) After establishment of the default EPS bearer, UE 10 transmits aspecific EPS bearer establishment request to MME 30 (S314). The messageherein is adapted to include, as the information on the flow, flowidentification information and QoS level. In the present embodiment, asthe TFT included in the flow identification information, “TFT1” isspecified.

(8) MME 30 receives the specific EPS bearer establishment request fromUE 10 and executes an establishment process of a specific EPS bearer(EPS bearer 2) (S316). The procedure is performed following theconventional procedure, by transmitting/receiving of control messagesbetween UE 10, eNB 50, MME 30, SGW 40 and PGW 20.

(9) PGW 20 transmits a flow (TFT1) selected by the request of UE 10 fromthe flows of UE 10 having been transmitted and received through EPSbearer 1, to UE 10 through the transfer path of EPS bearer 2. Thereby, apath for TFT1 is set up in EPS bearer 2 so that datatransmission/reception of TFT1 is started by use of the transfer path ofEPS bearer 2 (S318).

In this way, according to the present embodiment, by setting theattachment type to be “2”, it is possible to implement a similar processeven if the process is a conventional one in which all the flows aretransferred once to the default EPS bearer, followed by transfer to thespecific EPS bearer.

[4.1.3 Processing Flow in Control Station]

Referring now to an operation flow in FIG. 9, the processing in thecontrol station (PGW 20) accompanied by bearer establishment, in thepresent embodiment will be described.

First, a default EPS bearer establishment request is received (StepS10). In the present embodiment, MME 30 receives an attach request fromUE 10 first. MME 30 gives notice of a default EPS bearer establishmentrequest to PGW 20 as the procedure for establishing the default EPSbearer. At this time, the attachment type included in the default EPSbearer establishment request is retained. The default EPS bearer isestablished in response to this default EPS bearer establishment requestso as to establish a transfer path (EPS bearer 1) between PGW 20 and UE10 (Step S12).

Then, the attachment type indicated by the default EPS bearerestablishment request is identified (Step S14).

Here, when the attachment type is “1” (Step S14; attachment type “1”),MME 30 waits for an establishment request for a specific EPS bearer(Step S16). Then, when receiving a specific EPS bearer establishmentrequest from UE 10 (Step S16; Yes), MME 30 establishes a specific EPSbearer (EPS bearer 2) that guarantees QoS (Step S18). Then, PGW 20 setsup a flow path (route) designated by the specific EPS bearerestablishment request and starts communication (Step S20).

On the other hand, when the attachment type is “2” in Step S14 (StepS14; attachment type “2”), PGW 20 sets up a flow path (route) on thedefault EPS bearer and starts communication (Step S22).

In this way, when the attachment type is “2”, PGW 20 transmits all theflows of UE 10 that have been transmitted to the DSMIPv6 transfer path,to UE 10 through the specific EPS bearer (EPS bearer 1).

However, this is the same as the conventional handover; even when theflow of UE 10 to be handed over needs a QoS level, communication isperformed through the default bearer that does not satisfy the QoS levelcorresponding to the flow. That is, the flow is transmitted through thetransfer path that does not satisfy the necessary quality depending onthe application, hence there is a risk of the quality being markedlydeteriorated.

In this case, by setting the attachment type to be “1”, it is possibleto hand over the flow from the DEMIPv6 transfer path to the specific EPSbearer (EPS bearer 2) that is able to guarantee the QoS level withoutuse of the default EPS bearer.

4.2 The Second Embodiment

Next, the second embodiment will be described with reference to FIG. 10.The network configuration and apparatus configuration of this embodimentare the same as those of the first embodiment, so that detaileddescription is omitted. Further, since the procedures in which UE 10connects to a core network via access network B and establishes theDSMIPv6 transfer path for flow 1 and flow 2 are also the same, thedescription is omitted.

As the initial state at the time of a handover, UE 10 is performingcommunication of flow 1 and flow 2 through the DSMIPv6 transfer path byway of access network B. At the time of a handover, UE 10 enters thecoverage area of eNB 50 of access network A and transmits a handoverrequest by a control message using first transceiver 110 to execute ahandover procedure. This handover procedure is the same as the handoverprocedure described in the first embodiment with reference to FIG. 6 upto the stage where the default EPS bearer is established, or S206. Theprocedure that follows will be described with reference to FIG. 10.

(1) Differing from the first embodiment, UE 10 transmits a positionregister request for DSMIPv6 to PGW 20. This position register requestdemands establishment of a specific EPS bearer (S350). Here, the messageof this position register request should include the identificationinformation of UE 1, HoA of UE 10 and CoA as the positional information.Further, UE 10 transmits a position register request including the flowinformation and a QoS level for performing communication through theDSMIPv6 transfer path to be generated.

(2) PGW 20 having received the position register request implements aprocess of establishing a specified EPS bearer (EPS bearer 2) (S352).The procedure is performed following the conventional procedure, bytransmitting/receiving control messages between UE 10, eNB 50, MME 30,SGW 40 and PGW 20. The specific EPS bearer is a transfer path thatguarantees the QoS level required for the specific flow requested by UE10 and a transfer path for enabling communication between UE 10 and PGW20.

(3) PGW 20 and UE 10 set up a path for communication of the flow (TFT1in the present embodiment) present in the position register request. Bythis setup, the DSMIPv6 transfer path is switched to the specific EPSbearer transfer path to start communication (S354). Communication of theflows other than this is continued through the DSMIPv6 transfer path.

(4) After establishment of the specific EPS bearer, PGW 20 transmits aposition register response to UE 10 (S356).

Updating of flow management table 132 of UE 10 and flow management table232 of PGW 20 and the procedure of switching transfer paths may be donewhen the specific EPS bearer is established similarly to the firstembodiment, or may also be done when the position registering process ofDSMIPv6 is completed.

The difference of the present embodiment from the above first embodimentis that in the first embodiment MME 30 takes control of performingestablishment of the specific EPS bearer based on the specific EPSbearer establishment request of UE 10 whereas in the present embodimentPGW 20 takes control of establishment based on the position registerrequest of DSMIPv6.

4.3 The Third Embodiment

Next, the third embodiment will be described. The network configurationand apparatus configuration of this embodiment are the same as those ofthe first embodiment, so that detailed description is omitted. Further,since the procedures in which UE 10 connects to a core network viaaccess network B and establishes the DSMIPv6 transfer path for flow 1and flow 2 are also the same, the description is omitted.

As the initial state at the time of a handover, UE 10 is performingcommunication of flow 1 and flow 2 through the DSMIPv6 transfer path byway of access network B. At the time of a handover, UE 10 enters thecoverage area of eNB 50 of access network A and transmits a handoverrequest by a control message using first transceiver 110 to execute ahandover procedure. The handover procedure in the present embodimentwill be described with reference to FIG. 11.

(1) Initially, UE 10 and PGW 20 are transmitting/receiving data for flow1 (TFT1) and flow 2 (TFT2) through the DSMIPv6 transfer path (S400).

(2) Then, an attach request is transmitted from first transceiver 110 ofUE 10 to MME 30 (S402). The difference from the first embodiment is thatUE 10 requests an authentication process alone by attachment type “1” inlink with attachment and notifies that there is no need of establishmentof the default EPS bearer. Thereby, MME 30 performs an authenticationprocedure as receiving the attach request but do not perform a procedureof establishing the default EPS bearer.

(3) MME 30 having received the attach request, performs anauthentication and access permission processes by the procedure betweenUE 10 and eNB 50 following the conventional method (S406). MME 30performs the authentication and access permission processes based on thesubscriber identification information and the like of UE 10 included inthe attach request. Thereafter, MME 30 waits for receiving a specificEPS bearer establishment request from UE 10.

(4) When permitted to access, UE 10 transmits a specific EPS bearerestablishment request to MME 30 (S408). Here, the message of thespecific EPS bearer establishment request is transmitted including, asthe information on the flow, flow identification information (TFT1) andQoS level.

Thereby, an EPS bearer establishment process is implemented (S410) sothat a specific EPS bearer (EPS bearer 2) is established between UE 10and PGW 20. Then, a path is set up on the established EPS bearer 2 sothat transmitting/receiving of “TFT1” data is started (S412).

Further, similarly to S214 and S216 in the first embodiment, positionregister request and response are transmitted/received (S414 and S416).Updating of the flow management table and switching of transfer pathsand other procedures after establishment of the specific EPS bearer arethe same as those in the above embodiment, so that description isomitted.

The difference of the third embodiment from the first embodiment is thatupon the attach request (S402) at the timing of a handover, only theauthentication process is carried out without establishment of thedefault EPS bearer and then UE 10 transmits a specific EPS bearerestablishment request. Thereby, it is possible to complete a handovermore quickly without the need of establishing the default EPS bearer(EPS bearer 1), compared to the first embodiment.

Also, in the present embodiment, instead of requesting establishment ofa specific EPS bearer by notifying the flow information and QoS levelupon specific EPS bearer establishment request, the flow information andQoS level may be added so as to establish a specific EPS bearer, at thetime of PSMIPv6 position register request, similarly to the secondembodiment.

Further, it goes without saying that it is possible to perform ahandover procedure in a conventional manner as in the first embodimentwhen an attach request is made by attachment type “2”.

Moreover, though description was made that the position registerrequest/response are given after establishment of the specific EPSbearer (EPS bearer 2), position register complete notice/response fromPGW 20 to UE 10 may also be given. That is, PGW 20 transmits a positionregister complete notice that indicates that position register of UE 10after handover is completed, to UE 10. UE 10 transmits a response signalthat acknowledges the reception of the position register completenotice, to PGW 20. Further, switching of transfer paths at PGW 20 may betriggered by the position register complete notice/response procedurefrom PGW 20 to UE 10.

4.4 The Fourth Embodiment

Next, the fourth embodiment will be described. The network configurationand apparatus configuration of this embodiment are the same as those ofthe first embodiment, so that detailed description is omitted. Further,since the procedures in which UE 10 connects to a core network viaaccess network B and establishes the DSMIPv6 transfer path for flow 1and flow 2 are also the same, the description is omitted.

As the initial state at the time of a handover, UE 10 is performingcommunication of flow 1 and flow 2 through the DSMIPv6 transfer path byway of access network B. At the time of a handover, UE 10 enters thecoverage area of eNB 50 of access network A and transmits a handoverrequest by a control message using first transceiver 110 to execute ahandover procedure. Here, the procedure in the fourth embodiment will bedescribed with reference to FIG. 12.

(1) Initially, UE 10 and PGW 20 are transmitting/receiving data for flow1 (TFT1) and flow 2 (TFT2) through the DSMIPv6 transfer path (S500).

(2) Then, UE 10 transmits an attach request to MME 30 (S502). Here, theattach request of the present embodiment includes identificationinformation on UE 10 for authenticating UE 10 and permitting access. Thedifference from the first embodiment is that the attach request istransmitted with inclusion of the information (“TFT1” to be handed overand QoS level) on the flow to be handed over.

(3) MME 30 having received the attach request, performs anauthentication and access permission processes by the procedure betweenUE 10 and eNB 50 following the conventional method (S504). Specifically,MME 30 having received an attach request, transmits a default EPS bearerestablishment request to PGW 20. PGW 20, as receiving the default EPSbearer establishment request, executes a process of establishing an EPSbearer. Here, the default EPS bearer establishment request includesinformation on the flow to be handed over, included in the attachrequest.

(4) MME 30 implements a process of establishing a specific EPS bearer toUE 10 that was permitted to connect, similarly to S410 in FIG. 11 forthe third embodiment (S506).

Thereby, a specific EPS bearer (EPS bearer 2) is established between UE10 and PGW 20. Then, a path is set up on the established EPS bearer 2 sothat data transmission/reception of “TFT1” is started (S508).

Further, similarly to S214 and S216 in the first embodiment, positionregister request and response are transmitted/received (S510 and S512).Updating of the flow management table and switching of transfer pathsand other procedures after establishment of the specific EPS bearer arethe same as those in the above embodiment, so that description isomitted.

The difference of the present embodiment from the first embodiment isthat in the first embodiment the default EPS bearer is established firstat the time of a handover, then the specific EPS bearer is established,whereas in the fourth embodiment the specific EPS bearer can beestablished by the attach request. Thereby, the procedure ofestablishing the default EPS bearer is omitted so that it is possible tocomplete a handover more quickly, compared to the first embodiment.

Also, in the present embodiment, instead of requesting establishment ofa specific EPS bearer by notifying the flow information and QoS levelupon specific EPS bearer establishment request, the flow information andQoS level may be added so as to establish a specific EPS bearer, at thetime of PSMIPv6 position register request, similarly to the secondembodiment.

Further, if the attach request includes no flow information and QoSlevel, the conventional handover procedure can be carried out.

Moreover, in the present embodiment, though description was made thatthe position register request/response are given after establishment ofthe specific EPS bearer (EPS bearer 2), position register completenotice/response from PGW 20 to UE 10 may also be given. That is, PGW 20transmits a position register complete notice that indicates thatposition register of UE 10 after handover is completed, to UE 10. UE 10transmits a response signal that acknowledges the reception of theposition register complete notice, to PGW 20. Further, switching oftransfer paths at PGW 20 may be triggered by the position registercomplete notice/response procedure from PGW 20 to UE 10.

DESCRIPTION OF REFERENCE NUMERALS

-   1 mobile communication system    -   10 UE        -   100 controller        -   110 first transceiver        -   120 second transceiver        -   130 storage            -   132 flow management table        -   140 bearer establishment processor        -   150 DSMIPv6 processor        -   160 packet transceiver    -   20 PGW        -   200 controller        -   210 transceiver        -   230 storage            -   232 flow management table        -   240 bearer establishment processor        -   250 DSMIPv6 processor        -   260 packet transceiver    -   30 MME    -   40 SGW    -   50 eNB    -   60 AR

1. A mobile station comprising: a control circuit configured toestablish a first transfer path by way of a first access network betweenthe mobile station and a control station; wherein, when performingtransmission/reception of a plurality of flows with the control stationby using the first transfer path, the control circuit is configured toestablish a default EPS (Evolved Packet System) bearer by way of asecond access network between the mobile station and the control stationby transmitting an attach request for requesting a handover of a partialflow among the plurality of flows.
 2. A mobile station comprising: afirst transceiver configured to connect to a first access network; asecond transceiver configured to connect to a second access network; astorage configured to store 1) a first flow information which identifiesa first application, 2) a second flow information which identifies asecond application, 3) a first transfer path information whichcorresponds to the first flow information, and 4) a second transfer pathinformation which corresponds to the second flow information; a firsttransfer path establishment processor configured to establish, throughthe first transceiver, a first transfer path by way of the first accessnetwork by using the first flow information; a second transfer pathestablishment processor configured to establish, through the secondtransceiver, a second transfer path by way of the second access networkby using the second flow information; a packet transceiver configured totransmit and receive a packet; and a controller configured to controlthe first and second transceivers, the storage, the first and secondtransfer path establishment processors, and the packet transceiver.